Kaphael josia



IINHED STATES PATENT @rrrca RAPHAEL JOSIA, OF FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATES F LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPECIFICATION forming part of Letters Patent No. 265,504, dated October 3, 1882.

Application filed August 9, 1882. (No specimens.)

To all whom it may concern:

Be it known that I, RAPHAEL JOSIA,0fF1OI'- ence, Kingdom of Italy, have invented or discovered a new and useful Improvement in Compositions for Treating Sulphates of Lime for the Manufacture of Artificial Marble; and I do hereby declare the following to be a full, clear, concise, and exact description thereof.

In an application for Letters Patent of the United States filed March 2, 1882, I have described and made claim to an improved process of treating or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles of a material which I have termed cer- 1 taldite without pulverization of the gypsum. In said application I described briefly certain of the compounds or compositions which I employ to produce certain effects and the manner of using them, but stated that separate appli- 2o cations would be made for patents for such compositions.

The present application relates to one of the compositions so referred to, and it is designed for use in the process herein described in the 2 5 making of ivory-colored certaldite.

In carrying out the process referred to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such, by the use of suitable well-known 0 tools. The gypsum employed may be the ordinary native gypsum of commerce, though I prefer that which is comparatively pure or free from other matters of different composition. Such gypsum is usually obtained hydrated, or

' 5 containing a certain percentage of water in its composition; and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the whole of such water. This is done by subject- 0 ing it to the action of a graduallyincreasing heat, varying by preference with the size and quality of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration 5 is obtained. The length of time as well as the degree of heat required to effect the result will vary somewhat with the size, character, and purity of the gypsum employed; but

the temperature should not exceed 500 Fahrenheit, and both it and the time of exposure should be regulated. and limited with reference to securing uniformity of treatment throughout the entire mass or body. This operation may be known to be complete when a fracture of a test block presents a uniform white color. Any suitable drying or baking apparatus may be employed for this purpose, many such be ing known in kindred branches of the arts; but it should be of such construction that the material under treatment shall not be brought into direct contact with the tire. WVhen the desired eehydration has been effected the furnace is allowed to cool gradually, in order that the material under treatment may be cooled gradually; or the material may be removed 6 with due care to prevent breaking and exposure to moisture, and allowed to cool outside the furnace gradually until it is reduced in temperature sufficiently to permit handling with safety in its subsequent treatment, which is 0 designed to impart to it the desired color or tint and a high degree of insolubility and hardness throughout its mass. This step involves the use of the composition which forms the subjectnnatter of invention in the present application. This composition is formed of v the following elements: water, by weight, two hundred parts; alum, by weight, four to live parts; oxalic acid, by weight, two to two and one halfpa'rts; Brazil wood, (Pernambuco,) by 8 weight, one part; sulphuric acid, by weight, one-half part; rose of aniline, by weight, one one-hundredth to five one-thousandths part. These ingredients, being mixed in about the proportFons named, form a solution which is used as a bath, and to this end a suitable quanthe porosity and nature or physical and chemical condition of the article; but usually twelve hours (more or less) will suffice, though to secure uniformity of treatment and of result through the whole body or mass of the article I prefer repeated dippings--two, three, or more-say two or three seconds at first, and increasing gradually to one, two, three, or more minutes, more or less, with drying intervals of like increasing length between dippings, for half or three-quarters of an hour or so, after which the article may remain in the bath for twelve hours or so.

Vhile I do not limit my invention by any particular theory of chemical or physical reactions involved in the use of this bath as above described, I believe, with my present knowledge, that the salt (alum) held in solution, by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the ealcic sulphate and renders it more compact, harder, and less soluble, and that the oxalic acid of the bath acts chemically or physically upon the impurities or matters of other composition, (carbona es, &c.,) which are usually contained in greater or less quantities in native gypsums, and produces a like indurating effect upon them, though the salt may also have an indurating action upon the impurities present, and the acid may act in like manner more or less upon the calcic sulphate. The other elements of the bath act as coloring agents, and they impart to the article under treatment a color like ivory, the tint of which may be varied somewhat by varying the proportion of aniline employed, as above indicated.

By treating the article in .the bath as above described this color or tint will be diffused throughout its mass, though lines, veins, and markings ot'darker shades will usually appear, which are due probably to the impurities present in the calcic sulphate. By this bath a beautiful ivory color is secured of delicate tint as well as such a degree of hardness, density, and insolubility as renders the article (certaldite) an excellent and valuable material for use in the arts. When the article has been treated in the bath as above described it is removed and dried by exposure to the sun or to an equivalent furnace-heat for one or two hours, or by ordinary atmospheric exposure for two or three days, when it is ready for polishing and such other manipulation as may best tit it for its intended use, which may be done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications of the same, as circumstances may require, forms the subject-matter ofthe first application herein referred to. Neither do I limit my present invention to the particular way herein described of applying it, though I now believe this way or process to be the best. I also believe the proportions ofingredients which I have named in forming my improved composition to be the best for the purposes stated, and, among others, to secure a uniform degree of hardness and color throughout the mass of the article. If the solution be very strong, there is great danger of rendering the surface of the article hard very quickly, and thereby preventing the proper action of the bath upon the interior substance of the article; or it the solution be very weak too much time is required, and even then a proper degree of hardness, density, and insolubility is not secured; also, by the conjoint acti n of all the elements of the bath much better results are secured, especially upon native gypsum, than by a solution formed of a part of the elements. For these reasons I prefer to em ploy all the elements ot'the composition in substantially the proportions named; but such limits, though att'ording the best results, may be varied or exceeded somewhat and still obtain favorable results under skillful manipulation, and all such modifications employing the elements substantially as herein described in about the proportions set forth I consider as coming within my invention and claim.

I claim as my invention- The composition herein described for treating dehydrated gypsum, consisting substantially of water, alum, oxalic acid, Brazil wood, sulphuric acid, and rose ot'aniline, in about the proportions set forth.

In testimony whereof I have hereunto set my hand.

RAPHAEL JOSIA.

Witnesses:

GUIDO PANTALIONY, R. H. WHI'r'rLEsEY. 

